vector 使用

#include<set>
#include<map>
#include<vector>
using namespace std;
vector<int> a[100001];
int main()
{
	int x,y,n;
	char b[6];
	cin>>n;
	while(n--)
	{
		cin>>b;
		if(b[0]=='A')
		{
			cin>>x>>y;
			a[x].push_back(y);//将y存入容器数组 
		}
		if(b[0]=='Q')
		{
			cin>>x>>y;
			if(a[x].size()<y) //编号为x的帖子总的回复数小于y 
			 cout<<-1<<endl;
			else cout<<a[x][y-1]<<endl;//否则输出第y个回复的人的ID 
		}
	}
	return 0;
 } 
 

暴力

#include <bits/stdc++.h>
using namespace std;

struct Node{
    int x;
    int y;
};
vector<Node> v;

int main(){
    int n;
    cin>>n;
    while(n--){
        string op;
        cin>>op;
        if(op == "ADD"){
            Node usr;
            cin>>usr.x>>usr.y;
            v.push_back(usr);
        }
        else{
            int x1,y1,size = 0;
            cin>>x1>>y1;
            for(vector<Node>::iterator i = v.begin() ; i != v.end() ; i++){
                if((*i).x == x1){
                    size++;
                }
                if(size == y1){
                    cout<<(*i).y<<endl;
                    break;
                }
            }
            if(size < y1){
                cout<<"-1"<<endl;
            }
        }
    }
    return 0;
}